AA Double bearing adapter?

[vikingsven]

I see on the AA site that they are now marketing a double roller bearing adapter similar to Marlin's.

What the skinny?

Is it a completely new design or did Marlin give them the ok to sell his like the MC05???

[CruzrDave]

Here is our dual case bearing specs. This is A/A design but of course we saw this coming. 

Our MC07 Bearing (5209 double roller Max) has a Static Load Rating of 11,600 lbs and a Extend Dynamic Load Rating of 14,600lbs.

The MC05 and A/A old style which used a 6209 bearing has a SLR of 4550lbs and an EDLR of 8300lbs.

The stock Toyota RF1A main shaft bearing is a 6308 and has a SLR of 5850lbs and an EDLR of 11,400lbs.

I'm not sure but they might be using two 6109 sealed bearings. SLR is 3350lbs each and an EDLR of 5400lbs. Double those load ratings and you get 50% more then a 6209 and a little more then a stock 6308. Its defiantly an better design then the MC05 single bearing.

[BigMike]

It took me a while to gather the data for this post, and I did not know that Dave was replying to this same thread!! So here is my opinion:


Well, here is the problem. I have not seen a sample of the adapter and what bearings they use, but I can speculate that in order to maintain the same thickness of the adapter plate and relatively the same coupler length, there is not enough room on the coupler to use two of the 6209 Light duty bearings, the ones that A/A uses in the old-design Marlin Crawler kit that they have been retailing to the public for years now.

Our 5209W (W denotes "maximum capacity type") bearings have a 11,600 lb Static rating and a 14,600 lb Dynamic rating. They are 30.17mm wide and according to the book, the "Double row angular contact ball bearings meet the demand for increased axial and radial rigidity." Taking into consideration that in order to keep the adapter plate as thin as possible, we must use a coupler that only allows for a maximum space of 30-34mm to play with. The 5209W is 30.17mm which is about the widest bearing we can possibly fit on the coupler.

Now if A/A was to continue using their commonly used 6209 light series bearing, which is 19mm wide, then running two 6209 bearings with a spacer in between would at least 42+mm in length. There is not enough room on the coupler to have two 6209 bearings.

A/A's only other option is to run the Extra Light series 6109 bearing, which is just 16mm wide. I am not sure if this is what they have done, but there seems to be no other option. If this is true, then with two 6109 bearings and a spacer, the total length could be limited to about 36mm or so which should work.

But here is my concern with this:

Bearing Type	Width (mm)	Static Load (lb)	Dynamic Load (lb)
Marlin Crawler Double Roller 5209W	30.17	11,600	14,600
A/A current style, 6209	19.00	4,500	8,300
A/A new style, 6109?	16.00	3,350	5,400

In service, our Double Roller Bearing is 75.9% stronger than the current A/A setup, and a whooping 170.3% stronger than each of the bearings used in A/A's new double bearing adapter, depending on my above information.

So if we then double-up the 6109 bearing, which *appears* to be what A/A has done,

Bearing Type	Width (mm)	Static Load (lb)	Dynamic Load (lb)
A/A new style, 6109?, doubled-up	32.00+	6,700	10,800

So even still, running two Extra Light Duty bearings only amounts to 10,800 lbs while in motion, which is still 35.2% weaker than our one double roller Maximum Capacity type bearing used in all of our Crawlers.

It is true that the new A/A adapter is stronger than their current adapter, by at least 30.1%. Granted the two bearings are separated by some distance defined by the spacer which would yield more support, I just can't believe that two Extra Light Series bearings are stronger than one Maximum Capacity bearing. Especially two Extra Light series bearings that are, according to my book, "electric motor quality for applications where extra quietness is a requirement."

Of course this is all fine and dandy on paper. The real test of course will be out in the real world! We don't see our 5209W double roller bearings fail, A/A does have 6209 bearing failures, so hopefully by combining two Extra Light Duty bearings A/A will improve their track record a bit.

The bottom line is that Marlin could have stacked two stock mainshaft bearings together if he wanted to build his Crawlers with convenience and to save money, but he did not want to settle for using two bearings which, in the strict confins of this application, cannot possibly be better than one double roller bearing. I can say that Marlin was no dummy with his decision

[BigMike]

I'm not sure but they might be using two 6109 sealed bearings. SLR is 3350lbs each and an EDLR of 5400lbs. Double those load ratings and you get 50% more then a 6209 and a little more then a stock 6308.

Actually two 6109 bearings are only 30.1% stronger than a 6209 bearing, strictly by each bearings rating. A/A has spaced the two bearings apart a bit, which, surprisingly will NOT increase each bearing's load rating, but does increase the units axial rigidity.

When A/A advertises "Approx. 50% more bearing to shaft support than other kits on the market!" they are infact refering to their own adapter (our old-version MC05) and other very small vendors, such as Inchworm and JP Eater (no longer in business?)

That's funny because I would assume our market share is the same if not more than A/A's, and our "kit on the market" is still ~30% stronger. It is also interesting what "bearing to shaft support" really refers to

[CruzrDave]

Its just like Mike to copy what I already knew. You to slow!

[vikingsven]

Awesome.

Thanks for the replies guys. 

After looking at the AA picture a little closer you can see the 2 very thin bearings they are using. They look thinner than the original MC05 bearing to me.

[Ramrod]

i'm no expert at all on any of this and actually know nothing at all but couldnt they have made or had made for them some type of custom sized bearing?  ie: a narrow one?  either way it doesnt matter to me becuase I already have a mco7

[BigMike]

They could have but I think Marlin already looked into that, its way expensive.

When we first found the 5209W bearing, we had sourced it from Germany. That caused a lot of stock delays where we would have everything but the bearings if we had forgot to order more like in 2 months advance. Now we have about 3 or 4 different places where we have found them.

So the size bearing that we are using is just not common at all, so if we made some custom ones, I bet we would be the only manufacture in the world who would use them and it would cost a bundle to make them in such a small quanity

[Ramrod]

cool thanks for the lesson teach

[Hottrod81]

Thanks for the information.